The rate of elimination of inhalation agent is directly proportional to the degree of alveolar ventilation. Using Isocapnic Hyperpnoea (IH) device, it is possible to maintain constant end-tidal CO2 with increased minute ventilation. This is achieved by passively adding a flow of CO2 to the inspirate in proportion to increases in ventilation above the baseline. In animal and human studies IH shortens the time of awakening from isoflurane and sevoflurane anesthesia when manual positive pressure ventilation is applied. IH device could be used for spontaneous hyperpnoea as well. The investigators want to compare recovery times from sevoflurane anesthesia in patients with application of hypercapnic spontaneous hyperpnoea (HSH) versus the standard anesthesia protocol (controls). 44 patients ill be randomized to either HSH facilitated recovery, or conventional recovery (controls).The time intervals from the end of anesthesia (turning off the vaporizer) until recovery milestones will be recorded.

Further study details as provided by University Health Network, Toronto:

Primary Outcome Measures:

Time from the end of anesthesia to the readiness for post-anesthesia care unit (PACU) discharge. [ Time Frame: End of anesthesia (turning off the vaporizer) until readiness for PACU discharge, approximately 30 minutes to 2 hours ]

Secondary Outcome Measures:

Comparison of pain and sedation scores [ Time Frame: End of anesthesia (turning off the vaporizer) to PACU discharge, approximately 30 minutes to 2 hours ]

The O2 flow on the anesthetic machine will be set at 15 L/min. Ventilatory assistance will be performed to maintain O2 saturation >97% and end tidal CO2 at 35-45mmHg.

Other: Standard Anesthesia management for post surgical patients

The O2 flow on the anesthetic machine will be set at 15 L/min. Ventilatory assistance will be performed to maintain O2 saturation >97% and end tidal CO2 at 35-45mmHg.

Active Comparator: HSH Group

Patient will be disconnected from the anesthetic circuit and connected to the resuscitation bag attached to the IH system. With O2 flow of 2 L/min patient will be gently ventilated until recovery of the spontaneous ventilation. After starting spontaneous ventilation basal O2 flow will be adjusted to keep ETCO2 in range of 50-60 mm Hg or minute ventilation of 15-17 L/min, whichever occurs first.

Device: Hypercarbic Spontaneous Hyperpnoea

Patient will be disconnected from the anesthetic circuit and connected to the resuscitation bag attached to the IH system. With O2 flow of 2 L/min patient will be gently ventilated until recovery of the spontaneous ventilation. After starting spontaneous ventilation basal O2 flow will be adjusted to keep ETCO2 in range of 50-60 mm Hg or minute ventilation of 15-17 L/min, whichever occurs first.

Eligibility

Ages Eligible for Study:

18 Years to 80 Years (Adult, Senior)

Sexes Eligible for Study:

Female

Accepts Healthy Volunteers:

No

Criteria

Inclusion Criteria:

elective gynecological surgery

age 18-80

ASA I-III

informed consent

Exclusion Criteria:

ASA IV-V,

contra-indications to sevoflurane anesthesia or other anesthetics included in the protocol

history of cardiac or respiratory disease

intracranial pathology

alcohol or drug abuse

psychiatric illness and/or medications

Contacts and Locations

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For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01151267